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In this situation it is generally uncommon to talk about half-life in the first place, but sometimes people will describe the decay in terms of its "first half-life", "second half-life", etc., where the first half-life is defined as the time required for decay from the initial value to 50%, the second half-life is from 50% to 25%, and so on.
All of the remaining radioactive isotopes have half-lives that are less than an hour, and the majority of these have half-lives that are less than 3 minutes. This element has numerous meta states , with the most stable being 108m Ag (half-life 439 years), 110m Ag (half-life 249.86 days) and 106m Ag (half-life 8.28 days).
Krypton-81 has a half-life of about 229,000 years. Krypton-81 is used for dating ancient (50,000- to 800,000-year-old) groundwater and to determine their residence time in deep aquifers . One of the main technical limitations of the method is that it requires the sampling of very large volumes of water: several hundred liters or a few cubic ...
This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds. [1]
All other isotopes have half-lives less than 4 days, most less than an hour. There are also many isomers , the longest-lived of which is 120m1 Sb with half-life 5.76 days. Except for beryllium , antimony is the lightest element observed to have isotopes capable of alpha decay ; 104 Sb is seen to undergo this mode of decay.
The most stable radioisotope is 67 Cu with a half-life of 61.83 hours. Most of the others have half-lives under a minute. Unstable copper isotopes with atomic masses below 63 tend to undergo β + decay, while isotopes with atomic masses above 65 tend to undergo β − decay. 64 Cu decays by both β + and β −. [1]
Thallium-202 (half-life 12.23 days) can be made in a cyclotron [4] while thallium-204 (half-life 3.78 years) is made by the neutron activation of stable thallium in a nuclear reactor. [5] In the fully ionized state, the isotope 205 Tl 81+ becomes beta-radioactive, undergoing bound-state β − decay to 205 Pb 81+ with a half-life of 291 +33 − ...
The longest-lived radioisotope is 73 As with a half-life of 80 days. List of isotopes. Nuclide [n 1] Z N ... National Nuclear Data Center. "NuDat 2.x database".